New lanes are set to open Wednesday on eastbound State Route 78 along the border of San Marcos and Escondido, just west of Interstate 15, transportation officials said on Tuesday.

The new lanes are on the outer edge of the freeway, including two from Barham Drive to Nordahl Road and one from Woodland Parkway to Barham. They are expected to ease traffic as motorists merge on and off the freeway along the busy corridor, which is flanked by several large shopping centers and is not far from Cal State San Marcos.

“We’re pleased that these new lanes are opening and look forward to the traffic relief they will provide,” San Marcos Mayor Jim Desmond said in a news release.

The new lanes are the final piece of a $41.1 million package of improvements on 78, which included the widening of the Nordahl Road freeway ramps and bridge; new westbound merging lanes; and the reconfiguration of a crowded intersection just north of the freeway, at Nordahl and Montiel roads.

The projects were paid for through funds from San Marcos, Escondido and state and regional transportation agencies.